Factors That Affect Die Casting Die Life. Yulong Zhu Ryobi Die Casting Inc. (USA) David Schwam, Xuejun Zhu, John Wallace Case Western Reserve University. Design Related. Materials Related. Sharp Features Surface Finish Internal Cooling Lines Location. Steel Composition
Ryobi Die Casting Inc. (USA)
David Schwam, Xuejun Zhu, John Wallace
Case Western Reserve University
Many variables, including these listed on the previous
slide, act simultaneously to affect die life. In a production
environment it is difficult to separate these variables
and to determine their relative weight.
Quantify the effect of die lubricant application on die
temperature and die life: timing, duration and pressure
using the immersion test.
(36s cycle time, no spray)
(36s cycle time, 60 psi)
(36s cycle time, 45 psi)
(36s cycle time, 45 psi)
Note: min. temperature 370oF
30s cycle time: 3s traveling down, 7s immersing, 2s traveling up, 14s dwelling, 3s spraying and 1s air blowing
Note: min. temperature 300oF
36s cycle time: 3s traveling down, 7s immersing, 2s traveling upper, 14s dwelling,
3s spraying, 1s air blowing and another 6 dwelling
Longer spraying times depress the lows in cycle temperature,
while increasing the ΔT (=Tmax-Tmin), causing more cracking.
Higher spraying pressures can overcome the vapor blanket at
higher temperatures, increasing the cooling and the temperature
extremes. More cracking can be expected.
Longer cycle time leads to more cracking if the temperature drops more.
Die steels with slightly lower vanadium, silicon and carbon but higher molybdenum content seem to provide longer die life in many applications.
All modern die steels, when properly processed, will offer satisfactory performance in “routine” applications. Some will outperform others in demanding applications. The steel with the best combination of properties for the specific application will provide best die life.
Fast cooling rates(1,2) produce martensitic structures while avoiding
grain boundary carbides and pearlite.
and Fracture Toughness
Faster cooling rates during quenching provide better thermal fatigue resistance.
Higher hardness usually provides better thermal fatigue resistance.
This research work is supported by DOE funds provided through by ATI SMARRT program. NADCA and the members of Die Materials Committee approved this work and provided background. This work was performed at the Department of Materials Science and Engineering, Case Western Reserve University. The contribution of DOE, ATI, NADCA, and Case Western Reserve University are hereby acknowledged.
This publication was prepared with the support of the U.S. Department of Energy (DOE), Award No. DE-FC36-04GO14230.